This invention relates to the use of die attach adhesive, applied to the back side of a semiconductor wafer, to adhere a dicing tape to the wafer. The dicing tape supports the semiconductor during the dicing operations that singulate the wafer into individual semiconductor dies.
In a conventional process for fabricating semiconductor dies, a semiconductor wafer is processed to form a plurality of circuits on the top side of the wafer, and in later steps, the wafer is separated into individual dies along prescribed dicing lines. The individual die is attached to its chosen substrate by an adhesive applied between the back side of the die and the substrate. The adhesive is known as a die attach adhesive.
Rather than apply the die attach adhesive to the individual dies, it is more efficient to apply the adhesive to the back side of the wafer before dicing. Coated onto the semiconductor wafer, the die attach adhesive is known as a wafer back side coating.
In order to support the semiconductor wafer coated with the back side coating during the dicing operation, a support tape, known as a dicing tape, is adhered to the back side coating of the wafer. After coating, the wafer back side adhesive is B-staged, that is, partially cured to a less tacky state. The dicing tape typically comprises at least two layers, one being the carrier tape and the other being an adhesive film for contacting and adhering to the back side coating.
During the dicing operation, the dicing blade moves at tens of thousands revolutions per minute, creating a locally high temperature along the dicing lines. This higher temperature causes the tacky wafer back side coating to soften and mix with the dicing tape adhesive, potentially reducing the reliability of the wafer back side coating as a die attach adhesive.
This invention is an improvement on the assembly of dicing tape and semiconductor wafer coated on its back side with a die attach adhesive.